WARNING, ALOT OF QUESTIONS! (Screws, General)

[Traveller]

Hi All.

I have been screwdriving for years but probably have never done anything in the 'proper' way and would like to ask a few questions about this topic.

1) I understand that there are different drill bits that should be used on different types of wood/material, but is there also a case of using different drill bits to create holes for different types of SCREWS to be screwed into, for example, if you want to use screw 'x', you should drill the hole with drill bit 'y'?

2) I was sure that the specs 5 x 60 (for example) referred to the diameter and length of the screw, however, someone recently informed me that the '5' was the size of the head of the screw and not the diameter. Surely, that person was wrong?

3) In the above example, is '5' the diameter (assuming that I am correct about it being the diameter!) of only the centre axle of the screw or is it including the spiraly bits? (Sorry for the lack of knowledge of the correct technical terms for these things!)

4) In the same example again, should a 5mm drill bit be used to pre-drill (assuming the screws require pre-drilling) or should it be slightly smaller, e.g. 4mm?

5) Would would be the consequence of using a drill bit that is smaller in diameter than the screw?

6) If there is a problem with the above, then why can screws which do not require a hole to be pre-drilled be OK?

7) What should the depth of pre-drilling be in relation to the length of the screw?

8) What is the difference between screws whose spirally bits (thread??) go all the way to the head of the screw and those whose spirally bits start quite some way down the screw?

Sorry for the numerous questions!

Thanks.

 

[breezer]

1)no, drill biut depends on material and size of hole

2) inch 8s are 1 inch long and 8? wide

i really dont know where the 8 comes from but compare aninch 8 o a inch ten the body is wider

3)the spiraly bits are the thread (but i think there is another name, may be shank)

4) smaller

5) nothing its called a pilot hole, sometimes done to prevent material from splitting

6)see 5

7) same

8) one is conical the other isnt.

it could be argued the 100% threaded one grips better since it grips on its entire length should it become slightly loose

did you know that over 2 million 1/4 inch drill bits are sold every year, but no one really wants them? what they really want is the hole, so if you can make a hole that is quater inch that you can put where required you can make a fortune

 

[big-all]

ok here goes

imperial screws are known as number eg no4 6 7 8 10 12 [standard wire gauge i belive s.w.g.!!!]

metric are known by the thead measurement as in 3.0 3.5 4.0 4.5 5.0 6.0

for all reasonable comparasons [but not exact] no4=3m no6=3.5 no7=4 no8=4.5 no 10=5

so if you have a no10x2" screw thats a metric 5x50mm


you point no8 about the thread not going full length
shorter screws are used a lot with thin material sheet material hinges brackets handles ect
once you get up to around 2" your likley to be securing another thicker bit of material so you dont need full thread

 

[oilman]

http://www.wlfuller.com/html/wood_screw_chart.html

 

[Traveller]

Thanks for the replies; computer wasn't working, hence the late response!